Abstract

Space charge in high intensity beams is an important issue in accelerator physics. Due to the complicity of the problems, the most effective way of investigating its effect is by computer simulations. In the resent years, many space charge simulation methods have been developed and incorporated in various 2D or 3D multi-particle-tracking codes. It has becoming necessary to benchmark these methods against each other, and against experimental results. As a part of global effort, we present our initial comparison of the space charge methods incorporated in simulation codes ORBIT++, ORBIT and SIMPSONS. In this paper, the methods included in these codes are overviewed. The simulation results are presented and compared. Finally, from this study, the advantages and disadvantages of each method are discussed.

@article{osti_804612,
title = {SPACE CHARGE SIMULATION METHODS INCORPORATED IN SOME MULTI - PARTICLE TRACKING CODES AND THEIR RESULTS COMPARISON.},
author = {BEEBE - WANG,J. and LUCCIO,A.U. and D IMPERIO,N. and MACHIDA,S.},
abstractNote = {Space charge in high intensity beams is an important issue in accelerator physics. Due to the complicity of the problems, the most effective way of investigating its effect is by computer simulations. In the resent years, many space charge simulation methods have been developed and incorporated in various 2D or 3D multi-particle-tracking codes. It has becoming necessary to benchmark these methods against each other, and against experimental results. As a part of global effort, we present our initial comparison of the space charge methods incorporated in simulation codes ORBIT++, ORBIT and SIMPSONS. In this paper, the methods included in these codes are overviewed. The simulation results are presented and compared. Finally, from this study, the advantages and disadvantages of each method are discussed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jun 03 00:00:00 EDT 2002},
month = {Mon Jun 03 00:00:00 EDT 2002}
}

In Monte Carlo simulation, one is interested in the particle tracking process in two major ways. The first of these is in simply keeping track of where the particle is in relation to the various homogeneous zones that are used to simulate the spatial domain of interest through which the particle moves randomly in phase space. The second of these, which is becoming more and more important, is in forcing particles either in a preferred general direction (direction biasing) or to exactly intersect a particular zone. This latter process is essential in the statistical estimation variance reduction process in whichmore » the result of interest (e.g., particle detection) is forced to occur at each particle interaction point. These processes have many factors in common when treated mathematically. This paper describes experience in developing and using mathematical algorithms for these general tracking and forcing processes in the Monte Carlo modeling of nuclear well-logging tools and industrial tomographic devices.« less

A self-amplified spontaneous emission (SASE) free-electron laser (FEL) is under construction at the Advanced Photon Source (APS). Five FEL simulation codes were used in the design phase: GENESIS, GINGER, MEDUSA, RON, and TDA3D. Initial comparisons between each of these independent formulations show good agreement for the parameters of the APS SASE FEL.

Particle-tracking simulation is one of the scientific applications that is well-suited to parallel computations. At the Superconducting Super Collider, it has been theoretically and empirically demonstrated that particle tracking on a designed lattice can achieve very high parallel efficiency on a MIMD Intel iPSC/860 macene. The key to such success is the realization that the particles can be tracked independently without considering their interaction. The perfectly parallel nature of particle tracking is broken if the interaction effects between particles are included. The space charge introduces an electromagnetic force that will affect the motion of tracked particles in 3-D space. Formore » accurate modeling of the beam dynamics with space charge effects, one needs to solve three-dimensional Maxwell field equations, usually by a particle-in-cell (PIC) algorithm. This will require each particle to communicate with its neighbor grids to compute the momentum changes at each time step. It is expected that the 3-D PIC method will degrade parallel computer. In this paper, we describe an efficient scheme for implementing particle tracking with space charge effects on an INTEL iPSC/860 machine. Experimental results show that a parallel efficiency of 75% can be obtained.« less

In order to efficiently track charged particles over long times, most tracking codes use either analytic charge distributions or particle-in-cell (PIC) methods based on fast Fourier transforms (FFTs). While useful for theoretical studies, analytic distribution models do not allow accurate simulation of real machines. PIC calculations can utilize realistic space charge distributions, but these methods suffer from the presence of discretization errors. We examine the situation for particle tracking with space charge over long times, and consider possible ideas to improve the accuracy of such calculations.